Narrative:

We were pushed back from the gate on schedule. After pushback we started the engines, completed the required checklists and requested taxi clearance. The WX at the time was 90 overcast, 12 mi visibility, temperature 54, dew point 48, wind 240 at 7. It was still early and dark. Ground cleared us to runway 27L via right, west, C. I was doing checklists while the captain taxied the aircraft. We held short of runway 27L after crossing 27R. After pausing to determine the F/a briefing was completed, we completed the taxi and before takeoff checklist down to the line. I asked the captain if he was ready for takeoff and he said he was. I called the tower and we were cleared for takeoff. I did a taxi and before takeoff flow below the line and then read the checklist. The captain in the meantime was turning the aircraft onto the runway. After lining up the aircraft on the runway, he gave me control, since it was my takeoff. We reviewed our heading to turn to and made a normal takeoff. We were not advised until we arrived at our destination that we allegedly had taken off on a parallel taxiway to runway 27L. Supplemental information from acn 134373: I crossed taxiway and held at the CAT ii hold line south of aa. After clearance for takeoff, I taxied onto runway 27L observing the grass and approach light metal stands, and the white centerline lights. We took off. The copilot was making the takeoff, so I called out airspds and came out of the cockpit at rotation. I observed the end of the runway coming up as we lifted off.

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Original NASA ASRS Text

Title: ACR MLG ALLEGEDLY DEPARTS FROM TXWY.

Narrative: WE WERE PUSHED BACK FROM THE GATE ON SCHEDULE. AFTER PUSHBACK WE STARTED THE ENGS, COMPLETED THE REQUIRED CHKLISTS AND REQUESTED TAXI CLRNC. THE WX AT THE TIME WAS 90 OVCST, 12 MI VISIBILITY, TEMP 54, DEW POINT 48, WIND 240 AT 7. IT WAS STILL EARLY AND DARK. GND CLRED US TO RWY 27L VIA R, W, C. I WAS DOING CHKLISTS WHILE THE CAPT TAXIED THE ACFT. WE HELD SHORT OF RWY 27L AFTER XING 27R. AFTER PAUSING TO DETERMINE THE F/A BRIEFING WAS COMPLETED, WE COMPLETED THE TAXI AND BEFORE TKOF CHKLIST DOWN TO THE LINE. I ASKED THE CAPT IF HE WAS READY FOR TKOF AND HE SAID HE WAS. I CALLED THE TWR AND WE WERE CLRED FOR TKOF. I DID A TAXI AND BEFORE TKOF FLOW BELOW THE LINE AND THEN READ THE CHKLIST. THE CAPT IN THE MEANTIME WAS TURNING THE ACFT ONTO THE RWY. AFTER LINING UP THE ACFT ON THE RWY, HE GAVE ME CONTROL, SINCE IT WAS MY TKOF. WE REVIEWED OUR HDG TO TURN TO AND MADE A NORMAL TKOF. WE WERE NOT ADVISED UNTIL WE ARRIVED AT OUR DEST THAT WE ALLEGEDLY HAD TAKEN OFF ON A PARALLEL TXWY TO RWY 27L. SUPPLEMENTAL INFO FROM ACN 134373: I CROSSED TXWY AND HELD AT THE CAT II HOLD LINE S OF AA. AFTER CLRNC FOR TKOF, I TAXIED ONTO RWY 27L OBSERVING THE GRASS AND APCH LIGHT METAL STANDS, AND THE WHITE CENTERLINE LIGHTS. WE TOOK OFF. THE COPLT WAS MAKING THE TKOF, SO I CALLED OUT AIRSPDS AND CAME OUT OF THE COCKPIT AT ROTATION. I OBSERVED THE END OF THE RWY COMING UP AS WE LIFTED OFF.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.